Known art instruments include instruments having an internal reservoir portion for holding water, colored inks, paints, and other liquid art media (hereinafter collectively “ink”) and a brush portion connected to the reservoir portion for permitting the water or ink to pass through the brush portion for deposit on a desired surface to be painted. For example, U.S. Pat. No. 6,536,969 to Nishitani (assigned to Kuretake Co. Ltd) (the '969 patent) discloses an artist's instrument having a movable body and spring apparatus for controlling flow of ink out of a self-contained reservoir.
Another commercially available ink-dispensing brush is the Art-Kure Watercolour System Colour Sketch Brush (hereinafter the “Art-Kure brush”). The Art-Kure brush includes a body having an ink reservoir connected to a brush portion by an ink-dispensing assembly. The ink dispensing assembly includes a reservoir body having a closed end and an opposite open end, the open end having means for connecting the reservoir body to a nozzle and brush assembly. The ink-dispensing assembly further comprises an outer capillary tube, an inner capillary tube nested inside the outer capillary tube, an open plug inserted into one end of the outer capillary tube and acting as a travel stop for the inner capillary tube, and a secondary orifice restrictor. The secondary orifice restrictor includes a tube-receiving end having a recessed stepped portion for receiving the unencumbered end of the inner capillary tube and a stepped outer surface having a cross-sectional diameter that permits the tube-receiving end to be inserted into the unencumbered end of the outer capillary tube. The secondary orifice restrictor further includes an axial channel that protrudes along the entire axial length of the restrictor. The axial channel is generally cylindrical, and includes at least one stepped portion for receiving a solid pin having a first large-diameter end and an opposite small-diameter end. The large diameter end is inserted into the channel adjacent the tube-receiving end and is pushed up the channel until it reaches the stepped channel adjacent the opposite end of the secondary orifice restrictor, so that the large-diameter end is nearly flush with the terminal end of the channel adjacent the second end of the secondary orifice restrictor, thereby blocking flow through the secondary orifice restrictor. The small-diameter end of the pin protrudes into the channel provided in the inner capillary tube.
The Art-Kure brush's ink-dispensing assembly further includes a primary orifice restrictor having a protruding tube end, an opposite end, and a channel linking the two ends. The protruding tube end is configured so as to penetrate the axial channel of the secondary orifice restrictor and to displace the large-diameter end of the solid pin upon activation of the ink-dispensing system by a user. Displacing the pin permits ink to flow through the open plug into the outer capillary tube and then into the inner capillary tube, around the solid pin and through the axial channel of the secondary orifice restrictor, and through the axial channel of the primary orifice restrictor. The opposite end of the primary orifice restrictor is disposed in close proximity to a bristle portion, the bristle portion surrounded by a valve body having slotted sidewalls to permit the ink flowing from the primary orifice restrictor primarily around the outer perimeter bristles (versus uniformly through or between all bristles) and through the valve body and outside of the valve body, eventually reaching the tapered end of the brush portion for distribution onto a surface to be painted. The brush portion is nested inside the slotted valve body, and the slotted valve body is held in place by a nozzle threaded onto the threaded end of the reservoir body. The Art-Kure brush further includes a shipping ring that is situated between the threaded nozzle and the body, thereby preventing the full threading of the nozzle portion onto the reservoir body which would otherwise press the primary restrictor against the secondary restrictor to activate the secondary restrictor by compressing the pin to allow flow through the axial chamber of the secondary orifice restrictor. Removal of the shipping ring is accomplished by unscrewing a threaded nozzle and brush portion, removing the shipping ring, and re-tightening the threaded nozzle and brush portion onto the body. Re-tightening in this manner compresses a pin located in the secondary orifice restrictor, thereby opening a central passageway in the restrictor to allow ink to flow from the nested capillary tube system through the central passageway and the pin, and into the valve body and brush portion.
Despite some desirable features, the Art-Kure brush is prone to leaking after activation, whether in use or in storage. Leakage is especially prevalent from the brush end of the threaded nozzle portion, and is exacerbated by Art-Kure's use of thin inks having a viscosity of less than about below about 5 centipoise (cps) in conjunction with the slotted valve body, which allows ink to escape the nozzle body and to leak from any gap between the outer nozzle body and valve body, especially around the protruding bristle end of the nozzle. Additionally, thin ink that returns from outside of the valve body under user pressure travels primarily across the outer perimeter bristles of the bristle assembly, rather than evenly throughout all bristles of the bristle assembly. Moreover, once user pressure on the reservoir is released, the Art-Kure bristle portion does not self-wick to continually draw ink from the reservoir, but rather requires the user to re-apply reservoir pressure. Additionally, the Art-Kure brush allows ink to spurt from the brush under user pressure because the slotted structure of the valve body allows the low-viscosity ink to flow outside of the valve body and spurt from the gap between the outer bristles and the valve body, as well as from the gap between the valve body and the threaded nozzle. Such splattering occurs when a user firmly squeezes the reservoir body because the slotted valve body provides virtually no resistance to ink flow, and the flow is unchecked by the bristle assembly, thereby allowing substantially unimpeded flow in response to user pressure on the body. Furthermore, Art-Kure's inclusion of a very porous, open cell cylindrical sponge around the base of the slotted valve body adjacent the bristle base, in combination with ink below 5 cps, does not effectively control flow or mitigate against splatters resulting from firm squeezing of the body reservoir by a user. Additionally, it is believed that Art-Kure's nested capillary system is not optimized for smooth and consistent flow of ink, and particularly not for inks having viscosities of less than about 5 cps. Furthermore, Art-Kure's brush assembly is not suitable for inks having viscosity of greater than about 10 cps.
Thus, the complex assemblies of the '969 patent, the Art-Kure Brush, and other known artist's instruments fail to provide adequate, reliable control of ink to and through a brush portion as required for desirable, high-quality art projects. Moreover, known art instruments having self-contained fluid reservoirs lack features to render the instrument leak-proof during shipping, yet easy to activate for desirable fluid flow, self-wicking, and optimal controlled distribution onto a desired surface to be painted.
Therefore, what is required is an improved art instrument that provides smooth, even, controllable ink flow for inks of various preselected viscosities, and that is substantially leak-proof both before and after activation by a consumer.